DESCRIPTION: This study investigates mechanisms by which life stressors (e.g., family conflict, violence) affect children's immune system function, rate of reactivation of two ubiquitous childhood viruses (HHV-6 and HHV-7), and frequency of illnesses. A second goal is to identify child and family characteristics that either exacerbate or lessen the impact of stressors on immune/virologic outcomes. From an ongoing study of the frequency and consequences of reactivation of HHV-6 and HHV-7 in children, a sample of 170 sociodemographically diverse, 5-10 year old children will be selected. Life stress exposure, immune function parameters, rates of HHV-6 and HHV-7 reactivation, and health will be measured at intervals over a 3-year period. The immune parameters will include natural killer cell number and function, CD4+/CD8+ lymphocyte subsets, and the frequency of CD28-CD57+ positive cells. Incidents and type of illnesses will be recorded in weekly health diaries. Two indicators of stress exposure will be measured: a) lifetime cumulative exposure, and b) longitudinal changes in stress exposure. Relationships will be tested between both life stress indicators and immunologic, virologic, and illness outcomes. A specific focus is on understanding stress-health associations in children exposed to chronic high levels of life adversity. Children's temperament and the parenting competence of their primary caregivers will be tested as moderators of stress-health associations. Additionally, child attributes associated with psychosocial resilience will be tested as moderators. These attributes include children's attributions of control about adversity, and social and emotional competencies. Knowledge acquired by this study will enhance understanding of the mechanisms controlling life adversity and children's health and begin to define the specific cellular immune mechanisms that mediate stress and health relationships.